Etiology. Very little is known as to the cause of congenital clubfoot but it is not infrequently associated with other congenital deformities. It appears to be hereditary in a great many instances. The greater number of cases appear without definable cause, except perhaps from intra-uterine pressure. There are, however, a number of these cases that are associated with malformation of the bones of the foot and leg, such as absence of the scaphoid; defect of the tibia; fusion of a number of the tarsal bones.
Pathology. The sharp adduction and plantar flexion, at the tarsal joints, produce a deformed position of the foot. As a result of these, the heel is small and elevated; the dorsum of the foot is prominent; and the outer border usually, and, in extreme cases, the dorsum of the foot, bears the weight of the body in walking and in standing; the sole of the foot is bent sharply in, and twisted at the tarsal joint. In fact, all the bones are changed in shape, and the inner muscles, tendons and ligaments are shortened by contraction, while the ones to the outer side are lengthened.
The distortion of certain individual bones is of importance. The astragalus is the seat of the most important changes. It is tipped downward at its front end, and its posterior part articulates with the tibia, its anterior articular surface projecting under the skin; its neck is elongated and bent inward and downward, so that its scaphoid articulation faces inward and downward and not forward.
This is the most important change in clubfoot, because the anterior end of the astragalus, the head of the bone, carries inward and downward with it the scaphoid, the three cuneiforms, and the inner three metatarsal bones. The scaphoid articulates with the inner side rather than the front of the astragalus and, in extreme cases, forms a joint surface with the inner malleolus. It may be somewhat changed in shape, being flattened and drawn inward and upward.
The os calcis is generally poorly developed, and its front end is rotated downward, and bent inward; the outer surface of the bone is more convex and the inner surface more concave than normal, and since the anterior facet looks inward and downward, it carries with it the cuboid and the two external metatarsal bones. The changes in the other bones are not important; the chief obstacles to reduction lie in the os calcis and in the astragalus.
Soft Parts. The muscles, ligaments, tendons, and fascia at the lower and inner side of the foot are shortened, and lengthened at the outer and upper side. The plantar fascia being one of the chief obstacles to reduction, the tendons are displaced, especially those on the inner side of the foot.
Symptoms. Double clubfoot is usually accompanied by an awkward and unsteady gait, in which each foot is in turn lifted high to clear the foot on the ground, and the toeing in is, of course, excessive. The weight is borne on the outer side of the foot, and all elasticity of gait is absent.
On the outer border of the foot, where the weight is borne, callosities and bursae develop; the calves of the legs are small, and the knee joint may be lax.
The gait in single clubfoot is less awkward, but characterized by the same features. The foot is rigid in the deformed position, and in cases of marked deformity, the foot cannot be manipulated into the normal position.
Diagnosis. Congenital clubfoot cannot be mistaken for any other condition. The diagnosis is self-evident.